This invention relates to the catalytic oxidation of ammonia to oxides of nitrogen, particularly oxidation of ammonia over a mixed catalyst bed of cobalt and aluminum oxide.
The process and catalyst of cobalt oxide mixed with other metal oxides for the oxidation ammonia are known in U.S. Pat. No. 1,919,005 hereby incorporated by reference. Also, mixturs of cobalt oxide with other metals as catalyst in the oxidation of ammonia are known in U.S. Pat. No. 3,985,681, hereby incorporated by reference. The above patents set forth clearly the prior art process and catalysts. However, those operating such processes are continually looking for improved catalysts and yields. The process produces NO and NO.sub.2, hereinafter NO.sub.x.
Admixtures of metal oxides within individual pellets or co-catalyst is known art, and is believed to utilize complex chemistry that involves interactive or sequential reactions. However, alumina alone is regarded as an inert material under ammonia oxidation conditions. This can be demonstrated by its use either as a catalyst support bed or as a feed-gas preheater layer on top of the colbalt oxide catalyst bed; neither of which give improved yields of NO.sub.x.